Heart failure with preserved ejection fraction (HFpEF) is a difficult disease to diagnose due to nonspecific symptoms and clinical findings. The disease occurs in the elderly, who often have other illnesses and signs of aging that make diagnosis of heart failure more difficult. Recently, it has been suggested that HFpEF, which has primarily been thought to be a diastolic disease, is in fact multifactorial, with elements of abnormal systolic function and increased vascular stiffness playing a role in disease pathology. No treatment has been shown to reduce the high mortality of the disease. However, few studies have evaluated this population of patients during periods of increased physiologic stress, despite the consistent clinical presentation of impaired exercise tolerance with few symptoms at rest. This study explores the multifactorial physiology of HFpEF, with a detailed investigation of the specificity of abnormalities in contractile reserve and vascular stiffness for this disease, and exploration of the modifiability of these abnormalities. The techniques used are non-invasive, involving echoardiographic evaluation of cardiac function, and measurement of arterial stiffness using tonometry. The first aim of the study is to explore the specificity of a potential diagnostic test for HFpEF by investigating the change in ejection fraction before and after 2-adrenergic stimulation with low-dose dobutamine in HFpEF compared to other groups important to distinguish clinically, specifically patients with shortness of breath due to pulmonary disease, and those with hypertension and left ventricular hypertrophy without clinical heart failure. In the second aim, the study will investigate the ability of the calcium channel blocker, amlodipine, to restore normal contractile responses of the myocardium. In the third aim, the role of arterial stiffness in drug responses in HFpEF will be explored. It is anticipated that improved understanding of the complex physiology of this multifactorial disease gained through this study will lead to more rational design of large clinical trials studying promising agents for HFpEF that impact not only diastolic function, but contractile reserve and arterial properties as well. PUBLIC HEALTH RELEVANCE: Heart failure with preserved ejection fraction (HFpEF) accounts for over 50% of heart failure cases in the United States, affecting a primarily elderly population. No treatment has been shown to affect mortality in HFpEF, which is more than 50% at five years a hospitalization. This project explores the underlying cardiovascular physiology of patients with HFpEF with the goal of identifying new therapeutic targets that would allow improved treatment of this devastating disease.